U.S. Pat. No. 5,393,812 describes polyolefin compositions which are made flame retardant by a combination of a halogenated hydrocarbyl phosphate or phosphonate ester flame retardant in combination with a alkoxyamine functional hindered amine, but there is no suggestion that the hindered amine itself is responsible for the flame retardancy, but rather that the hindered amine is preventing delustering and other undesirable effects from occurring in these polyolefin compositions.
European Application No. 0 792 911 A2, discloses that alkoxyamine functional hindered amines are effective when used to enhance the flame retarding efficacy of tris(trihalogenopentyl) phosphate flame retardants.
U.S. Pat. No. 6,117,995 discloses that certain N-alkoxy hindered amines may be used as flame retardants for organic polymers. Copending U.S. application Ser. No. 09/502,239, filed Nov. 3, 1999, and Ser. No. 09/714,717, filed Nov.16, 2000, disclose the use of certain N-alkoxy hindered amines as flame retardants.
The flame retardant (FR) market today is comprised of products which function to interfere with the combustion process by chemical and/or physical means. Mechanistically these FRs have been proposed to function during combustion of an article in either the gas phase, the condensed phase or both. The organohalogens are proposed to generate halogen species (e.g. HX) which interferes in the gas phase with free radical organic “fuel” from the polymer substrate. Synergists are proposed to react with HX to form additional chemical species with interfere with combustion in the gas phase, such as reaction of antimony oxide with HX to form antimony halide and water vapor. Still other flame retardant classes are proposed to impart efficacy in the “condensed” phase such as forming a protective char layer on the polyester, or forming an intumescent or foaming on the polymer surface. The char or intumescent layer is thought either to prevent organic fuel from migrating from the polymer into the vapor phase where it can fuel combustion, or the char can act as a thermal shield to protect the underlying polymer article from thermally induced decomposition and generation of fuel. Phosphorus compound of various classes (e.g. halo- or non-halogenated) are an example. Further still, other classes of compounds are proposed to function in the condensed and/or vapor phase. Metal hydrates or metal oxides are proposed to generate water vapor under thermal conditions, the water acting to dilute the fuel mix in the combustion zone and to remove heat from the flame zone via conversion of water to vapor. Alumina trihydrate, magnesium hydroxide or oxide, and other compounds are reported to function in this way.
These state of the art chemistries described above have various detrimental aspects in addition to the effective flame retarding attributes mentioned. Certain organobrominated compounds are under governmental scrutiny for the generation of toxic by-products during the production or combustion such as dioxanes from polybrominated diphenyl oxides. Certain metal-containing flame retardants, notably antimony oxides, are under scrutiny for worker exposure and toxicity reasons. Antimony oxides often contain trace amounts of arsenic compounds which are suspected carcinogens. Overall, a growing concern has arisen regarding the generation of smoke and toxic gases which are evolved from these flame retardants during a fire. While the classic FRs may be effective combustion suppressants, the toxic gases they form pose a threat to human exposure.
The instant invention alleviates some of the detrimental aspects of the current state of the art which the use of large amounts of commercial flame retardants pose. The present synergist compounds are non-halogenated and free of heavy metals, thus avoiding generation of corrosive HX gases and avoiding exposure to toxic metals. In some applications, the instant invention provides a direct replacement for current FR systems where the instant synergist compounds provide a complimentary enhancement or synergistic system (e.g. antimony oxide replacement in ABS) where good flame retardancy can be achieved by using less classic FR agent in the presence of the instant synergist compounds.
Hydroxylamine stabilizers are disclosed in U.S. Pat. Nos. 4,590,231, 4,612,393, 4,649,221, 4,668,721, 4,691,015, 4,696,964, 4,703,073, 4,720,517, 4,757,102, 4,782,105, 4,831,134, 4,876,300, 5,006,577, 5,019,285, 5,064,883, 5,185,448 and 5,235,056.
Nitrone stabilizers of component are described in U.S. Pat. No. 4,898,901.
U.S. Pat. Nos. 4,666,962, 4,666,963, 4,678,826, 4,753,972, 4,757,102, 4,760,179, 4,929,657, 5,057,563, 5,021,479, 5,045,583 and 5,185,448 disclose the use of various substituted hydroxylamine stabilizers towards the stabilization of organic materials.
U.S. Pat. Nos. 5,081,300, 5,162,408, 5,844,029, 5,880,191 and 5,922,794 disclose the use of saturated hydrocarbon amine oxides towards the stabilization of thermoplastic resins.
Benzofuranone stabilizers are disclosed for example in U.S. Pat. Nos. 4,325,863; 4,338,244; 5,175,312; 5,216,052; 5,252,643; 5,369,159; 5,488,117; 5,356,966; 5,367,008; 5,428,162; 5,428,177; 5,614,572; 5,883,165 and 5,516,920.
Quinone methide stabilizers are disclosed for example in U.S. Pat. Nos. 5,583,247, 5,616,774, 5,670,692 and 5,750,765.
O-alkenyl substituted hydroxylamine stabilizers are disclosed in U.S. Pat. No. 5,045,583.
Non-hindered alkoxyamine stabilizers are disclosed in U.S. Pat. No. 5,185,448.